How do I Know
by multi-fangirl123
Summary: Jacklyn and Nikki Piper, normal siblings, or at least that's what they think when one day they're transported to a universe where their favorite TV shows and movies exist. Multi-crossover with dr Who, RotG, Sherlock, Merlin, and some mentions of Supernatural. JackxOC
1. Chapter 1

**So this is a multi crossover with RotG, doctor Who, Sherlock supernatural and merlin a lot I know. my first fan fic ever so please try and go easy on me. I got this idea from the story k9 and BW And I'm not trying to copy it. Updates may be slow because I am a slow writer also CONSTRUCTIVE criticism is welcome **

**ENJOY!**

I hate my alarm clock. I hate school even more. Although it has been quite good since my sister and I moved to London. *que internal squealing* I know what you're thinking "who is this person blabbing her mouth off and seems to be obsessed with London?" well you will just have to wait and see.

"Jackie get up or you'll be late for school."

Shoot. OK OK you got me. My name is Jacklyn Piper. I'm 14, American, and live in London. My big sister (the one who can't keep her mouth shut) goes to college here in London. Her name is Nikki Piper, she has shot dirty blond hair and dark brown eyes like mine and is tall for her age like me. And as for the London obsession, my sister and I both watch Doctor Who, Sherlock, and Merlin. We also have our own obsession, were not totally in sync. My other obsession is the movie Rise of the Guardians, and she has Supernatural. But I've been talking too much let's just get to the story.

"I'm coming." I yelled back lazily.

I put on some random shirt my favorite blue sweatshirt over that, some jeans, dark blue converse and tied my brown hair into a pony tail.

After my usual morning routine I rode my bike to school. Let's hope today will be quick. There is going to be a replay of my favorite Doctor Who episode, The Day of the Doctor. Thankfully the school day did go by rather quickly. For dinner Nikki made pizza (yes! something I'll eat). After we were talking when we heard thunder crack really loud.

"Were we expecting a thunder storm tonight?" I asked.

"I don't think so." Nikki replied. That was when a really strong gust of wind came from the window and knocked us out.

When I woke up Nikki was still out like a light. I soon gave up trying to wake her up after even freezing cold water didn't wake her up. That was when I noticed something heavy in the pocket of my sweatshirt which is where I put my replica of the tenth Doctors sonic screwdriver. When I got it I almost screamed. The screwdriver was no longer fake and plastic it now looked real and it is medal. I pressed the button and it sounded a lot more realistic then the old one. Then the lights went out and when I pressed the button, they came back on. At this point I was fangirling out. Then Nikki started to wake up, so to freak her out I pressed the button on my sonic.

"Am I being punked?" She asked.

"Yes and no." I replied

She then finally looked at me and nearly screamed at what I was holding. "Is that the real sonic screwdriver?" She asked

"No shiz Sherlock." Then I had a brain storm. I dragged Nikki into her room and dug around to find her vortex manipulator and her replica of the eleventh Doctors sonic screwdriver and handed them to her. Then we both screamed and fangirled for like 5 minutes. I know what we were both thinking at that time 'this day can't get any better'. Then I realized the time was 7:15 and I was so going to be late for school. Fortunately a certain vortex manipulator got me there, and after school Nikki picked me up with it. I was getting bored (somehow in this situation) and got my phone out to text one of my friends. But instead of my very thick phone with a black it case, I pulled out a very expensive looking iPhone. Apparently this day can get much better. I felt something else in my pocket, a blank paper in a case. At first I didn't know what it was then I started to think about torchwood for some reason and the next thing I know the paper said Jacklyn Piper torchwood agent. "Of course psychic paper, how could I be so oblivious." I said to myself.

_Jacky_

As soon as I heard the voice I looked outside to see the moon. Could be. No it couldn't. It is. The Man in the Moon is talking to me. I internally screamed then answered Manny "Yes Manny?"

_I see you're happy with the changes I made with your life._

"Happy? I'm overjoyed. So I have tons of questions."

_Shoot._

"Great. First what other stuff do Nikki and I get out this?"

_You each have the ability to deduce, you have Merlin's magic, and Nikki has Castile's wings._

"That is so cool! Next question why are we here?"

_You and Nikki are in these stories._

"I hate to argue with you Manny but we aren't in these TV shows and movie. Hell we didn't even know they were real."

_The writers are wrong. If you have no more questions let me tell you what you're going to do first. _

"Actually I have one more question, how do I use Merlin's power without a magic book?"

_I completely forgot about the book, here._

Then the moon got brighter, there was some sparkles and the book was next to me. "Thank you."

_The first thing you will do is help the guardians defeat Pitch Black. I have told the guardians that you will be one as well as Jack Frost. Also Jackie you will have to get jack to trust you right away. Nikki is going to help Sam and dean in… season 2 episode 5 I believe._

"OK. So how do I get jack to trust me when I walk into the ally?"

_You will be there when he wakes up as Jack Frost_

"So where and when is that?"

_You will go to Burgess February 1, 1776._

"Thank you."

_No problem. Goodbye._

"Bye."

I am freaking out inside. I'm going to meet the guardians. Best day of my life. "Nikki get the vortex manipulator we're going on a trip."

**A/N gosh done with the first chapter I'm a little nervous to see how it comes out oh well**

**Until next time, here's a cookie for my reader(s) (::)**


	2. Chapter 2

**Did you miss me? *cricket* of course you did **

**ENJOY!**

**February 1, 1776**

Nikki dropped me off and I told her to pick me up in a month. I put on proper clothing for the time, but nothing much, just a plain brown dress. Then I saw him The Jack Frost definitely the best day of my life. Just remember Jacky don't freak out, don't run away, and no spoilers. Let's hope my plan works. I go around the corner bumping into someone who I meant to bump into. "Oh, I'm so sorry." I said trying to play dumb. He has Hair white as snow, deep blue eyes, and is wearing a plain white shirt with a cape and pants that end on the calves.

"Oh no I wasn't looking where I was going… you can see me?!"

"Yes I can."

"You must think that's a weird question."

"I do. I'm Jacky Piper. What is your name?"

"I'm Jack, Jack Frost."

"Nice to meet you Jack."

"So where were you going?"

"No where in particular, I just go where the wind takes me."

"So do you want to walk with me to no where in particular."

"Are you asking me on a date, because if you are I must say my sister is way to overprotective of me… not." We were both laughing at that.

"You know you're pretty funny."

"Oh come on I'm not that funny. I'm sure you are more funny." I know you're funnier.

"I actually don't know if I'm funny or not." His face seemed sad now.

"Hey come on people will see you at some point it may be far to come but I can assure you it will come."

"You're right it will come eventually."

"Yes! That is the sprit I like. Now we go to where ever the wind takes us."

After that we did go where ever the wind takes us. It's only been a few days since I met Jack, and for some reason every time I look at him I get all bubbly inside. Should I tell him I have magic or that I'm not even from this time period? If I want him to trust me I have to show that I trust him. I'm going to tell him. "Jack, I have to tell you something."

"Shoot"

"Well, we've known each other for a bit and I feel like I can trust you. Icandomagicandi'matimetraveler." I said as quickly as I could.

"What?"

"I have magic and I'm kind of from the future."

"What does that mean?"

"It means I know what's going to happen in the future, and I can do this." I got up and found a random branch, focused, and sure enough my eyes turned gold and the branch moved. I made it go around the snow and end at Jacks feet.

"That is so cool!"

"Really so you're not freaked out about it?"

"How could I, I control winter and snow."

"Oh right." I couldn't say anything else because there was a huge gust of wind that knocked me into Jack. We both went tumbling to the ground and I landed on top of Jack. I couldn't help the blush that was undoubtly showing. I could see the blush on Jack face though. "Did you tell the wind to do that?"

"What me." He pretended to look shocked. I don't know what was happening, but we were getting closer to each other until we our lips touched. I don't know why but I liked it. It was better than I expected my first kiss to be. Yes, I never expected it to be with Jack Frost, but I had a good idea of how I thought it would go down. We broke the kiss for air, and went into a more heated kiss. He snaked his arms around my waist and pulled me in more as I started to play with his hair. I whined a little as we broke the kiss.

"Jacky I like you, will you go out with me?"

"All you had to do is ask."

"So is that a yes?"

"Why don't I do this then you can decide." And I kissed him again. I was then surprised when he managed to get his tong into my mouth, but I broke it and rolled off him. There was something else I had to tell him.

"I'd say that is a yes."

"Jack there is one more thing."

"Go ahead."

"Well, I'm leaving at the end of the month." Jack looked like he was about to cry. "I'm sorry but I'm not leaving right now, so we should enjoy this moment ok." I gave him a sympathetic smile and hugged him. We were like this for what seemed like forever, and I didn't want to let go but I knew he had work to do. "Come on, you got to do your job. I think we're still in London, and I know how much you like freezing people's buts off."

"You're right we should live in the moment, the moment we just had."

"That's the spirit…I think." He then slowly snaked an arm around my waist pulling me in and kissed me again. I wrapped my arms around his neck and depend the kiss. When we broke the kiss for air I said "Definitely that moment." And we were on our way.

One day I found my iPod in the pocket of my bag and I was relieved to have some tech crap from my time (if it can't be indoor plumbing or pizza it might as well be an iPod) .While Jack was out making winter in Paris, France, I was listening to my favorite Disney song 'I Won't Say I'm in Love' from Hercules in a nearby forest. Meg is my absolute favorite Disney 'princess' (exception Bell) because she doesn't need a knight in shining armor to save her.

(_Meg _**muses**)

_If there's a prize for rotten judgment_

_I guess I've already won that_

_No man is worth the aggravation _

_That's ancient history _

_Been there done that_

**Who'd 'ya think you're kidding'**

**He's the earth and heaven to you**

**Try to keep it hidden**

**Honey we can see right through you**

(_oh nooooo_)

**Girl you can't conceal **

**it we know how you feel and who you're thinking of**

_oooooooh_

_no chance no way I won't say it no no_

**you swoon you sigh why deny it uh-oh**

_it's to cliché I won't say I'm in love_

I guess I was singing out loud because Jack tackled me from behind. "If you don't love me why are you here?!"

"Why would you think that?" I said as calmly as I could wall taking my ear buds out. Wait he doesn't know how song writing works "Oh. You thought that I was singing my feelings. Jack I do love you." He didn't look like he believed me so I put one of the ear buds in his ear. Luckily I knew 'You had me at Hello' by Olivia Holt was next.

_I can here you coming from a mile away _

_my pulse stops racing from the words that you say_

_and you say so many of them like you don't have a clue_

_that I'm sign sealed delivered with a stamp on_

_you don't have to try to hard _

_you already have my heart_

_you don't got a thing to prove _

_I'm already into you_

_So_

_Hold, hold, hold, hold me tight now _

_cause so, so good to go _

_don't say don't say good night _

_you know you had me at hello you had me at hello _

"Jack I do love you, I just like the songs on here." I held up my iPod.

"I'm sorry."

"It's okay. You were just afraid. We all get scared sometimes. Come on you're done with work it's couple time." I said slightly smirking. "You know what that means."

"A make out session?"

"What else would it be." I said coming closer to him. Our faces are inches away and I couldn't take it anymore. I slammed my lips agents his and he snaked his arms around my waist while I wrapped my arms around his neck, gently caressing his soft hair and grabbing a fist full of his blue hoodie. I playfully bit his lip which made him moan. After a while I had to breathe but Jack wouldn't let go. I couldn't help liking this, it was the best make out session we've ever had. The kiss was now aggressive and I couldn't help giving out a low moan myself. I could feel him smirking into the kiss and I playfully hit him.

But everything must come to an end and this kiss is no exception. Jack and I finally broke the kiss and I was panting from lack of oxygen. But it was all worth it because Jack Frost is the best boyfriend ever. He's romantic, handsome, funny, and a good kisser… no a really good kisser.

"So when can I get a kiss like that again?" jack asked.

"It depends on how seductive you're being." I joked

"Okay. So if I did this…" He then picked me up by my thighs so my legs were wrapped around his waist.

"That may work." I joked again.

"Come on we've got to go to sleep." He said while putting me down. We have to lay in the snow but I don't mind as long as I'm with my boyfriend I can be happy anywhere.

The month was coming to an end and Jack and I spent every second together, mostly kissing but he did his job of bringing winter to the world. Then the day we both were dreading, the day Nikki came to pick me up. Jack and I were by his lake kissing, and talking, but mostly kissing. We were in the middle of kissing when Nikki came with the vortex manipulator. But Jack didn't know it was my sister and nearly shot her.

"Jacky, cut the lip locking and let's go." Nikki said.

"Nice to see you too sis. Let me just say goodbye to Jack… in privet."

"Ok as long as you two keep it rated R. I'll just be behind this tree." She smirked and went behind the tree she pointed to.

"Thank you." Although I know all too well that she is going to be listening in.

"Do you really have to go?" Jack asked.

"Sadly yes, but be patent, I promise you I will come back." He then put his lips on mine. I tried to get some air but he wouldn't let go. But it should be enough for 300 years so I didn't mind. We finally broke the kiss. Then I was off with Nikki. I felt so bad for leaving Jack but it had to be done. But just imagine being alone for 300 years I would die.

**A/N yes second chapter done please review tell me if it's good, if it's bad or what I can improve on. **

**BYE!**


	3. Chapter 3

**A/N ok that might have taken long but I couldn't figure out how to update **

**Disclaimer: I (sadly) own nothing except for my OCs**

**ENJOY!**

3 days before Easter, present day.

I still feel bad about leaving Jack, but I couldn't disobey Manny, but that look on jacks face, I will never get it out of my head. I'm in the ally where Bunny gets Jack and brings them to the pole. Right now I'm just in the shadow waiting for a good time to come in.

"Been a long time, blizzard of 68 I believe. Easter Sunday wasn't it?"

That's my que. "Oh come on Bunny don't tell me you're still upset about that little blizzard." I said coming out of the shadows.

"Jacky!" Jack said running to me and kissing me… in front of our favorite Easter kangaroo, but I didn't care, I'm just glade Jack isn't mad at me.

"Good to see you Frosty, you look better than the last time I saw you."

"Well the last time you saw me the love of my life left for 300 years."

"Jack were you cheating on me?" I joked.

"Ahem."

"Oh, yes I forgot our favorite Easter kangaroo is still here, lovely."

"Right, so how do you two know each other?"

"Is that any of your business?"

"Oh well, I've got other business to take care of. Fellas." As soon as he said that 2 yetis grabbed me and Jack, shoved us each into a sack, and tossed us. I felt a little dizzy, but not so much that I couldn't stand. When I got out of the sack jack was helping me up, and of course the Guardians were there. Here we go. "Wow you've got to be kidding me." I whispered.

"There they are Jack Frost and friend." Said a thick Russian accent, which must be North. "Hope the yetis treated you well."

"Oh yah, cause we love being shoved in a sack and tossed through a magic portal." Jack said

"Oh good, that was my idea."

"You know bunny, obviously." North stated.

"Obviously." Jack mumbled.

"And the Tooth fairy."

"Hello Jack I've heard a lot about you, and your teeth!"

"My-my what?"

"Open up." Tooth ordered and opened Jacks mouth. "Are they really as white as they say? Oh they do sparkle like freshly fallen snow." I'm laughing hysterically now. "Girls pull yourselves together, let's not disgrace the uniform."

"And sandy… sandy? Wake up!" North yelled.

"I'm Jacky."

"Hey ho, dose anyone want to tell me why we're here?" then sandy made these sand signs above his head that were going too fast to read. "That's not really helping but thanks little man"

"Jack must have done something really bad to get you four together." I finally spoke up.

Jack nodded and asked "Am I on the naughty list?"

"Ha, on naughty list, you hold record. But no matter now we are wiping clean slate."

"How come?" I asked.

"Good question." Bunny commented

"How come! I tell you how come. Now you both are Guardians!" just then trumpets started playing and some of Tooths fairies tried to give us paper necklaces. Some elves offered Jack shoes and I was trying to hold back a laugh the whole time. Plus being Jacks girlfriend, I know his annoyance limits, which is in 3…2…1. Jack pounded is staff on the floor, and frost spread on the floor. Right on que.

"What makes you think we want to be Guardians?"

North started laughing and said "Of course you do. Music"

"No music!" I said.

"Look this is flattering and all, but you don't want me." Jack started "You're all hard work and deadlines, and I'm snowballs and fun times, I'm not a Guardian."

"That's exactly what I said." Bunny commented.

"And I have to agree with my boyfriend over here, we're not Guardians. Plus I'm, human. A vary special human, but at the end of the day I'm human." I stated.

"Oh, and what makes you so special?" bunny asked.

"You are looking at the reincarnation of Merlin and time traveler." I replied. I've never seen Bunny look star struck… it's priceless.

"Guys, I don't think you understand what it is we do." Tooth started. "Each of those lights is a child."

"A child who believes, and good or bad naughty or nice we protect them." North finished. "Tooth, fingers out of mouth." Sure enough tooth had her fingers in my boyfriends mouth

"Oh, sorry. There beautiful." Tooth apologized. For some reason I felt jealous. Oh well.

"Ok no more wishy washy Pitch is out there doing who knows what." North stated.

"You mean the Bogyman?" jack asked

"Yes. When Pitch threatens us he threatens them as well." North replied.

"All the more reason to pick someone more qualified." I said. Hey I have to participate.

"Pick? You think we pick? No, you were chosen like we were all chosen by Man in Moon."

Jack perked up at that. "What?"

"Last night Jack he chose both of you." Tooth informed.

"Maybe." And of course Bunny had to say that.

"The Man in the Moon, he talks to you?"

"See you cannot say no, it is destiny."

"How come he didn't tell Jack that himself?"

"After 300 years this is his answer? To spend eternity like you guys cooped in some-some hide out looking for new ways to bribe kids. No that's not for me. No offense."

"How is that not offensive? You know what I think we just dodged a bullet. What do these clowns know about bringing joy to children anyway?"

I was about to go into the kill but Jack got there first. "Ah you ever hear of a snow day? I know it's no hardboiled egg but kids like what I do."

"But none of them believe in you, do they it's like you don't even exist."

"You better shut your trap or you're not only going to feel the wrath of my boyfriend, but Merlin the wizard as well." I started to but in.

"No the kangaroo's right." Jack just ruined my thunder.

"What did you call me? I'm not a kangaroo mate."

"Oh and this whole time I thought you were. If you're not a kangaroo what are you?"

"I'm a bunny the Easter bunny, people believe in me." Right now I want to smack Bunny across the face, and I was about to when North stepped in.

"Jack, Jacky, walk with me."

**Hope you like it **


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